1. Field of the Invention
The present invention relates to a system that dissipates heat from optical pickup units in optical drives.
2. Description of Related Art
A conventional optical drive (e.g., a compact disk player) typically includes a stationary optical unit, a movable optical unit, and an actuator. The stationary optical unit generally includes a laser diode, a half mirror, and a photodetector. The laser diode generates a light beam that is reflected by the half mirror onto the movable optical unit. The movable optical unit typically includes an objective lens that focuses the light beam on a spinning optical disk.
The actuator aligns the movable optical unit with the tracks of the optical disk so that the light beam reflects off the lands and pits of the tracks. The reflected light beam travels back through the movable optical unit and back to the stationary optical unit. The light beam is transmitted through the half mirror onto the photodetector where the varying intensity of the light is changed to electrical signals.
Optical drives are becoming smaller so they can be integrated into portable devices including laptop computers and personal digital assistants (PDAs). Close arrangement and integration of components help to miniaturize optical drives. For example, the stationary and movable optical units described above can be integrated into a single component (an integrated optical head) called xe2x80x9coptical pickup unitxe2x80x9d or xe2x80x9cOPUxe2x80x9d. An actuator arm can then be used to place the OPU over the tracks of a spinning medium.
The integration of the stationary and movable optical units imposes new design restraints on optical drives. The close proximity of the OPU components within the confines of a small optical drive (e.g., 52 by 10 by 40 millimeters) requires a careful thermal design so that the heat buildup does not cause a failure of the OPU. Accordingly, what is needed is a system that dissipates heat from by the OPU.
An optical assembly includes an optical head, an actuator arm for positioning the optical head, and a plate for transferring thermal energy between the optical head and the actuator arm. In one embodiment, the optical head is mounted atop a first portion of the plate and at least a second portion of the plate is mounted to the actuator arm. In another embodiment, the optical assembly further includes a flex circuit for carrying signals between the optical head and a printed circuit board. In one implementation, the optical head is mounted atop the plate, the plate is mounted atop the flex circuit, and at least one wire couples at least one pad on the flex circuit to at least one pad on the optical head through at least one cutout in the plate. In another implementation, the flex circuit is mounted atop the plate, the optical head is mounted atop the plate, and at least one wire couples at least one pad on the flex circuit to at least one pad on the optical head.
The thermally conductive plate helps to dissipate heat from the optical head to the surroundings by increasing the overall surface area. In an embodiment where a portion of the plate is mounted to the actuator arm, the actuator arm also helps to dissipate heat from the optical pickup unit to the surroundings by further increasing the overall surface area. By dissipating heat to the soundings, the optical pickup unit is less likely to fail because of heat buildup.